Metal-working machine



Sept. 2; 1930.I J. B. ARMITAGE METAL WORKING MACHINE 1925 14 Sheets-Sheet Filed Dec. 14

INVENTOR Sept. 2, 193@u J. E. ARMITAGE METAL WORKING MACHINE Filed DeC. 14, 1325 14 Sheets-Sheet 2 NVEN'TOR ATTGRNEY SPt- 2, 1930 J. B. ARMITAGE 1,174,692

METAL WORKING MACHINE I Filed Dec. 14, 1925 14 Sheets-Sheet 3 I I INVENToR 5` Figi f 7B l sePt' 2; 1930 J. B. ARMITAGE METAL WORKING MACHINE 14 sheets-sheet 4 Filed Dec. 14, 1925 lvENoR BY A f3 v 6MM/q ATTORNEY Sept '2, 19304Av J. B. .Am/MAGE METAL WORKING MACHINE Filed Bec. 14, 1925 14 Sheets--SheekI 5 .4 m J Nerv emm u, MON mom a @vom .ullllillr INVENTOR G 1 T x IIW... V r lluhil. 11.!II. f 1 v N 0% .v nl n l U Z W 1 Smm 2, 193ML J. E3. ANMTTAGE v LTMWM HETAL WORKING MACHINE Fic 99.0. 1 4, 1925 Sheets-Sheet 6 6. //ZZ/ 7,72% I i l S f 255 X. 260e 252er F 7 22% lNvENToRT 1g. [I: 2 6,z E M M ze@ B 66 v, 5 y 4 T y/55a a ATTORNEY 4Sep-t. 2, 19305 J. B. ARMITAE 1,774,692

METAL WORKING MACHINE Film nec. 14, 192s '14 sheets-sheet '7 um N sept 2, 1930.: J. B. ARMITAGE 1,774,692

METAL WORKING MACHINE Filed nec. 14, 1925 14 sheets-sheet 8 Fig. 9

ATTORN EY Fig. l0

Septi 2, 1930.- J. B. ARMITAGE METAL WORKING MACHINE Filed Dec. 14, 1925 14 Sheets-Sheet 9 ONM NNN

NVENTOR ATTORNEY Sept. 2, 1930. J. B. ARMITAGE HETAL WORKING MACHINE Find 1166.14, 1925 14 sheets-sheet' 1o nom INVENTOR BY ff Y ATTORNEY Sept 2, 1930- J. B. ARMITAGE METAL WORKING MACHINE Filed Dec. 14, 192;-, 14 sheets-sheet 11 ATTORNEY Sept. 2, 1930.1 J. B. ARMITAGE METAL WORKING MACvI-IINE Filed Dnc. 14, 1925 14 Sheets-Sheet 12 x v INVENTOR ATTORNEY f Sept. 2,. 1930.l

METAL WORKING MACHINE Filed Dec. 14, 1925 14 Sheets-Sheet 15 F'l 50 INVENTOR g M744 W7,

A BY

ATTORNEY J. B. ARMITAGE 1,774,692

Sept. l2, 1930. .1.B. ARMITAGE y 1,774,692

METAL WORKING 'MACHINE Filed D60. 14, l925 14 Sheets-Sheet 14 ATTORNEY Patented sept'. 2, 1930 JOSEPH B. ARMITAGE, on MILWAUKEE,

TRECKER CORPORATIOALCE WEST ALLIs, WISCONSIN, A CORPORATION OE WIs-' CONSIN PATENT` OFFICE WISCONSIN, ASSIGNOR T0 KEARNEY &

METAL-WORKING MACHINE.

Application led December 14, 1925. Serial No. 75,265.

rllhis invention relates generally tomachine tools and more particularly to milling machines.

lt is an object of this invention to devise a machine capable of simultaneously milling grooves or jiiutes in aV number of different work pieces whereby the productive capacity of the machine is greatly increased without a corresponding increase of the mechanism required and to provide control mechanism therefor, whereby the duties of the operator are limited to' replacement of the work pieces, thus greatly increasing the number of machines which an operator may attend.

Another object is to devise a machine capable of producing a number of grooves or liutes in the same piece of work, one after another, accurately spaced and positioned, by the means of mechanism which is selfcontrolled and capable of operating simultaneously upon a number of Work pieces.

Another object is to devise a machine such as vdescribed above, in which work pieces previously milled with either one or several lgrooves of a certain form, may be later replaced accurately in the same machine and one or several grooves of the same or another form may be milled 1n a certain desired position relative to the'first milled grooves.

Another object is to provide an improved machine adapted for the millingr of helical grooves such for instance as the grooves of twist drills. I

Another object is to provide a slow feed mechanism in addition to the normal feed mechanism, and control'mechanism therefor, whereby it may be available for use at the beginning of each feed movement if required, and if in use may be adjusted to operatefor a longer or shorter interval.

vof movement for the return travel.

Anotherobject relates.A to a drop table mechanism, thatis to say mechanism for Another object is to combine a drop table mechanism with mechanism for altering the plane i relative depth of cut at the opposite ends of a Work piece, whereby grooves may be cut either having equal depth or having a predetermined difference in the depthat different portions of the groove, and whereby 4incombination with other features of the mechanism disclosed, twist drills may be milled having a predetermined difference in the thickness of the web at different points in thelength.

Another objectrelates to indexing mechanism and to indexing mechanism in combination with drop table mechanism, and to lcontrol mechanism therefor whereby the vinchne'and the specific mechanism thereof for the'accomplishment of the above mentioned objects and other objects which will be ap-4 v parent from the accompanying drawings, description and claims.

In the drawings, like reference characters indicate the same parts in each of the several views in which:

Fig. l is a partial side elevation of a milling machine embodying the invention, the View being taken from the right. To v,the left of Fig. l is -considered the front of the machine, the ol'aertos'position being to the left of Fig. l and facing the machine.

Fig. 2 is a front elevation of the complete machine. l

F i g. 3 is a top or plan vie'w of the complete machine except that a part of 'the driving motor is broken away. and the upper support for the cutter arbor is largely broken away to show the cutters.

Fig. 4 is a rear view of the work supports and associated control mechanism taken along a line 4 4 of Fig. 3 and enlarged.

Fig. 5 is a sectional elevation along line 5-5of Fig. 4 and also along line 5--5 of Fig. 3 and enla rged.

Fig. 5A is a se'ction along line a-a of Fig. 5.

Fig. 6 is a sectionalelevation mainly along line 6 6 of Fig. 2 and enlarged, the lower right hand portion however being a section along a somewhat different line 'a trifle to the right of line 6 6 of Fig. 2 to illustrate a 'portion of the control mechanism as will be along along line 11-11 of Fig. 1 enlarged and more exactly along line 11'-11 of Fig. 12.

Fig. 12 is a cross section through automatic feed change geai` case along line 1,2-12 of Fig. 11. f l

Fig: 13 is an end view of mechanism shown in Fig. 11.

Fig. Meis a section through a trigger arm a portion of the i' shown in Fig. 12 along line lei-14 of Fig.v

12, and alsoshows the end of a lever arm 204C from Fig. 9, with which the trigger arm is associated.

Fig. 15 is a developed section through a driving train as will be later described.

Fig. 16 is an end vie'w ofadjusting worm and case shown in -F ig. 15.

Fig. 17 is an end `view of echange gear bracket shown in Fig. 15.

Fig. 18 is a top view of a portion of the controlv trips and some ofthe associated mechanism, being in part a partial section at the rear along l-ine 18-18 of Fig. 2 and in part a partial section along line 18M-1Sa of Fig. 2.

Fig. 19 is apartial section through the mechanism along line 19-19 of Fig. 18.

Fig. 19A is a portion of a cam groove in one or' the clutch devices. i

Fig. 20 is a 'partial'section through the mechanism along line 20-20 of Fig. 18.

Fig. 21 is a. projected view of a portion of the mechanism shown in Fig. 18.

Fig. 22 is a projected view of a portion of the mechanism shown in Fig. 21.

Fig. 23 is a partial horizontal section through the headstock along line 23-23 of Fig. 2.

Fig. 24 is partly a top view, partly in horizontal sectionthrough the tailstock along line 24--24 of Fig. 2.

Fig. 25 is a developed sectional portion of one of the tailstock spindles and its drive shaft. A l

Fig. 26 is avvertical section along line 2(326 of Fig. 24 showing mechanism for withdrawing the tailstock spindles.

Fig. 27 is a partial section along line 27-27 of Fig. 6.

Fig. 28 is an enlarged section through the work holding end of one of the head centers showing an equalizing driver for a particular type of Work piepe.

Fig. 29 is a horizontal section along line 2.9-29 of Fig. 11. i

Fig. 30 is a developed' section along line 3Q-3() of Fig. 10. i

Figs. 31-#32-33-34show. in detail the form and association of certain parts also shown inFigs. 11 and 12.

Fig. 351 is an enlargedview of a portion of Fig. l1.

' A column or main support 1 rotatably supports the tool driving spindle 2 together with its driving mechanism. Projecting from spindle 2 and driven thereby is a cutter arbor 3 upon which are mounted a number of cutters 4. Column 1 'also slidably supports a knee or support 5'vertically adjustable thereon, and upon which is slidably mounted a saddle or work support 6' for i adjustment toward and from the column 1. Saddle 6 is provided with a guideWay or slide in which a work support 7 may reciprocate in a path of movement disposed at an angle to the axis of arbor 3, the angle being indicated by the generalarrangement Vof the parts in Fig. 3. Pivoted in suitable trunnions for oscillation or swinging movement relative to the support 7 is a support generally denoted by the numeral 8, a section along the trunnion or pivot bein shown in Fig. 7. A number of vhead spin les each generally denoted by the numerals 9, Fig. 3, are rotatably supported from the support 8 but fixed against axial movement, and a number of tail spindles cach generallydenoted by the numeral l0, Fig. 3. are rotatably supported in a tailstock 11, adjustable on support 8 and have a limited iudividual adjustment for securing the work pieces between the head and tail centers.

General description of the madri/1m Referring to Fig. 3, a work piece it. is shown in position between a pair of the opposed head and tail centers. Similar work pieces are inserted between each of the pairs of head and tail centers and are clamped by thrustingthe tail Vspindles strongly in the direction of the head spindles, and by the means of driving dogs. After the work pieces are in place, a cycle of work movement"is begun, the operator determining when the cycle shall begin by moving a suitable control part. The support 7 together with the work travels at a quick traverse rate to the right and having arrived at the extreme right 'of its travel the support 7 stops, the support VAfter the cutters have traveled suiliciently tained for the balance of the. travel to the left. It mayhere be explained thata cutter and especially oneof the form required for milling deep grooves cuts much more smoothly, with less vibration and chatter and with less unbalanced strain tending tov force the work froml its supports or holders after it has entered into the work piece to the full depth of its cut, and it is to reduce the chatter and strain incidental to the brief period of starting into the cut that the slow feed mechanism is provided. Arriving at the limit of left travel' the support 8 swings downwardly so that the cutters are clear of the work. If only one groove is to be machined in each piece the mechanism is automatically stopped in this position for loading. If. additional grooves are to be machined the supports continuevto move and a rapid traverse to the right begins.. During the rapid traverse to the right, if. more than one groove is to-be cut, the work is indexed to make" the second cut, and when at the end of .this rapid traverse to the right, the support 8 swings up to a cutting position, the work has been turned to l start a new cut, following which a slow feed begins to the leftto be later changed -to a faster or normal feed to the left, which continues until the second cut is completed. The support 8 then swings downwardly on its pivot so that the work clears thel cutters, and

.if the work requires only two cuts to comf plete it, the movements stop in the down position for reloading new work pieces. If

however additional cuts are required, the

necessary other strokes are completed before the movements stop.

All-the above is accomplished automatieA cally, that is to' say the movements are controlled from the power movement of the parts except reloading of the work and starting the mechanism to perform a new cycle, and by comparatively simple means which is to be described in detail.

' that the above cycle is ,merely representative and various changes may be effected therein. As suggested above, the indexing of the work pieces is optional and need not be perl formed at all, or if performed, the work may be indexed once or several times before the movements are stopped. It is also optional .as to whether the slow feed'is to be used. The mechanism wherebyv this is effected may be rendered inoperative in which case the feed stroke will start immediately at a normal feed rate. Both the length of cutting stroke. and the rate of the normal feed are adjust able or variable to accommodate different work pieces. In addition, means are .provided to slowly rotate the 4work pieces during their advance whereby a spiral vgroove as it is generally known, or more accurately speaking, a helical groove, ma`y be cut in the It is to be noted i work pieces each time the work is fed for-- ward. v

The above and other features of the meclr anism provided will be more fully explained in connection with the descriptionv of the mechanism.

Illaf'fn clutch tml drive 15o cutters A main drive shaft 1.2 Fig. 1) may be actuated from any convenient power source` such as an electric motor shown in part and denoted generally by the numeral 13 and sup- -ported by a bracket 14 from a main stationary support or column 1. In the drawingthe motor is shown coupled to .sh-a ft 12 bythe means .of a conventional coupling generally denoted by the numeral 15. A pinion 12a fixed with shaft 12 meshe'swith a gearl 16 fixed upon a rotatable shaft 17 together with a pinion 16,

which meshes with a gear 18 freely rotatable and sfidable on a shaft 19. A gear 20 is fixed on shaft 19 and the gears 18 andQO are provided on'the'ir adjacent faces with com pivoted on a shaft 25 and having a` shoe 26 enga,f {ing v the 'annular groove 18b on the extended hub of the gear 18; the levers Q4 and QSbeing connected by the means of arod QT pivoted at its ends in the respectivewleversl Thus when hand lever 21 is moved in the one direction the clutch teeth 18'l and 20 will engage` whereby the motor l13 will drive gear 20 and when moved in the'other direction gear Q0 and all parts connected to be driven therefrom will be idle` the clutch thus formed being a main clutch for stopping the movement ofthe entire machine except the several parts directly coupled to ntotor 13. This main clutch is generally denoted by the letter B, Fig. 1.

Cutter support am] dri/1c Referring to Fig. 1, the gear 20 meshes with a gear 28 keyed on a shaft 29 and which meshes with gear 30 fixed on a shaft 31 upon which is slidably splined a unitary pair of gears 32a and 32h of different diameters, and adapted to be shifted in the one direction whereu )on rear 32 will engage and drive ir C! C D hand lever 36 outside the column and fixed'on a pivot -pin or shaft 87 which extends inside the column and carries a lever 38 having a fork 39 pivoted therewith and engaging the faces of the gear 32".

A cutter or tool arbor 8 isprovided with an end 3 fixed in the end ,efspindle 2 to be supported and driven thereby; and in turn supports and drives thescveral cutters 4 (see Fig. The arbor and cutters are provided with supplementary snpportsnin the form of a structure coacting with a plurality of overarms 40 and also with a drive supplementary to the drive through the arbor end 3, This support from the double overarms and the supplementary drive have been fully disclosed in a previous application Serial 12,254 filed February 28. 1925, and will nothere be further described since the details thereof form no part of the present invention. A

harness or brace 41 Fig. 2) is adjustably Vfixed with the supporting structure depending from overarms 40 by the means of bolts 42,- the adjustment being provided by the means of the slotted bolt -holes 43 and the brace 43 is clamped or iixed with a kneeA 5 by the means of a clamp member 44 which is tightened by the means of a bolt 45.

By the above described mechanism the arbor 3 and cutters 4 are provided with a very rigid support and a drive from the motor 13, the drive being' capable of interruption by the-meansof the main `clutch B. Ifdriven ,the arbor may be selectively operated at different speeds according to the position of the gear pair consisting of gears 32a and 82". It is to be noted that the gear pair is merely representative of a great variety of speed chan-ge mechanisms for altering the. speed of the arbor. Y

Tram/Mavica. for Hz@ movenze/2f work support f The work support 7 together with all the mechanism supported therefrom is slidable in the saddle 6 as previously noted. For power movement thereof, a transmission is provided as will now befdescribed.

The shaft 29 (see Fig. 1) is extended toward the rear and carries a gear 46 fixed thereon which drives a gear 47 through idlers 48 and 49 rotatably supported in a ease or housing 5() iixed at the rear of column 1. The gear 47 is `fixed on ashaft 51 rotatably supported and having fixed on its front end the member 52 which is the driving member of an extensible universal joint shaft of well known construction and generally denoted in.

Fig. 1 by the numeral A driven member 54 of joint shaft 53 is fixed on a shaft 55, see Figs. 6 and 8, rotatably supported from the work support- 7. The gear 47 stands to the right of column 1 from which gear 46 'is supported and the idler gears y48 and 49 are in fact larger than the relative proportions `column 1. At the front end of shaft 55 is fixed a bevel Year 56 meshing with a bevel y n n gear 5r fixed on a shaft 58 (see Flgs. 9 and 30) havincr suitable bearinefs in a case or housinfY n C 2*) 7, (see Figs. 6 and 3) 'fixed with or integral with the work support 7. A gear 59 fixed on shaft 58 meshes with and drives a gear 66 (see Figs. 8, 9-and 30) supported for independent rotation on a fixed stud 61. By the above described mechanism the gear 60 is rotated at a constant quick traverse rate whenever the main clutch B is engaged.

A spur gear 62 (see Fig. 6) is fixed on the front end of a shaft 55 and meshes with a gear 68. on 'a shaft 64 (Figs. 6, 8, 11, 12 and se). A Sima e5 (Figs. e, 10, 11,712 and 3e) is driven from shaft 64 by the means ef feed change mechanism to be later described which is supported in a case or housing 66 (see Fig.

3 ete.) and which provides normal feed rate for the cutting travel of the Work which may be changedlto obtain a preferred rate and also provides, if desired, a relatively very slow starting rate whereby thework may travel at a rate considerably less than the normal feed rate until the cutters are well started into the cut. Fixed on the shaft 65 is a worm 67 (Figs. 9, 10 and 30) meshing with a worm wheel 68.`

The worm Wheel 68 is, by the above de'- scribed mechanism given a continuous feed motion whenever the main clutch B is engaged and the relationship of the parts is such that the worm wheel 68 and the s iur gear 60. which has been previously described as having a quick traverse movement, revolve in opposite directions. lVheel 68 is provided with clutch teeth 68 and gear 60 with clutch 'teeth 60l (Figs. 8, 9 and 30). The wheel and gear are spaced apart on the stud 61 by the means'of a sleeve 69 and a clutch member 7()n having fixedtherewith a gear 7() freely rotatable on sleeve 69is provided with clutch teeth 70bon the one end and Clutch teeth 70c on the other end, the clutch teeth being respectively complementary to the teeth .on

.wheel 68 and gear 60 and being adapted to engage with and be driven bythe complementary teeth when the member 70 is shifted in the proper direction. VGear 76 meshes with an idler gear 71. (see particularly Fig.8), suitably supported and which in turn meshes with agear 72 fixed to revolve with a bevel gear 73 and with a supporting shaft 74. The bevel gear 73 meshes with a bevel gear 75,

.fixed to revolve with a spur gear 76 on the stud 77. Gear 76 meshes with a gear 78 fixed on the lead screw 79 (Figs. 1 and 8) which is journaled in a bearing 7c in the work support lill liti

7 but isprevented from axial movement thereimbeing restrained to move with the tion if the clutch teeth 70b are engaged with .the complementary clutch teeth 60a. The screw 79 is' in threaded engagement with a nut 80 fixedin. the saddle 6 and when the screw is rotated as described the work support is forced to travel in the one or the other direction iny accordance with the direction of 'rotation of thescrew. The relationship 'is such that when the screw is 'rotated from the 'engagement of clutch teeth 70c with clutch teeth 68a, the resulting direction of movement of work support 7 is toward the A leftin F ig. 2 and at a feeding rate as previously described; and when the clutch teeth 7Gb-60a are engaged the direction of movement of support 7 is toward the right in Fig. 2 and at a rapid traverse rate.

Feed chan-ge' transmission case or housing 7*- (see Figs. 36-11-12 and 29) and is provided with a bearing 66a (Figs. 12 and 29) for the forward end of the extended shaft 64 upon which is removably fixed a feed change gea-r 81 (see. Figs. 12 and 29) which meshes with a feed change gear 8.2 removably lixed on a short shaft 83' (Fig. 12)

rotatably supported in housing 66 and provided on the end opposite the change gear `end with an enlarged portion having clutch Y lteeth .88s. ,Shaft 83 is in axial alignmentwith the previously described shaft 65', whichv isextended forward at- 65a and has slidably keyed upon it a clutch member 84 having clutch teeth 84a complementary to the clutch teeth 83a and adapted to engage therewith and be driven therebywhen member 84 is moved in the proper direction, inV which case shaft 65 will be operated through the change gears 81 and 82'and will transmit the rate detemined thereby to the worm Wheel 68. The change gears 81 and 82 are reversible in their position in. the train and also may be replaced-by other gears of different ratio which also may be reversible, the gears 81 and 82 being in fact merely representative of agreat variety of change gears of dierent ratio,

which may be interchangeably and reversibly mounted on shafts 64 and 83 whereby a great variety of feed rates may be selectively available for driving the support 7 4through the mechanism previously described.

The shaft 64 also has fixed upon it or integraltherewith a gear 224 (Figs. -12 and 29) which meshes with a gear 85 having a stem 0r elongated hub 85a (Figs. 6 and 12) provided with a suitable bearing in the supportin housing and in axial alignment with shaft 65 which'passes through an axialbore in the hub, the gear and shaft being independentlly rotatable: The gear 85 is provided with.

clutch teeth 85b (Fig. 12) suitably disposed to be engaged by complementary clutch teeth 84b on the clutch member 84 when the clutch member is shifted in the proper direction. )V hen the member 84 is so shifted the shaft 65 will be driven through the gears 224 and 85 and will then drive the wormvheel 68 from whichv the support 7 may be driven-by the mechanism previously described and since the driving gear 224 is comparatively very small and the driven gear 85 Icomparatively -very large, the support movement resulting from such a drive will be at a comparatively veryslo'w feed rate. v

It vwill thus be seen that in accordance w1th VAthe position of the clutch member 84 either a predetermined-variable normal feed rate or a very slowalternative feed rate may be available to feed the support 7.

Support 8 and flr'op table mechanism for mising and lowering same yThe numeral 8 as previously noted has been generally applied to an oscillating work support pivoted for movement about the axis of a shaft 87 (seeFigs. 4,6. 7, etc.). Several members including a head stockmember 88 and a platform or table member 8a-on which the tailstock l1 is slidably adjustable are pivoted together te move about this axis in order todrop the work pieces out of contact with the cutters during the quick return traverse stroke. Referring to" Fig. 7, the bushings 89 and 9() are xed inthe support 7, and their outside diametersA provide vbearings upon which themember 88 is pivoted, the member 8a being rigidly fixed with member 88, or integral therewith. At its left end the part 8a is provided with'bearings for a pin or shaft 91 having eccentric portions 91L (see Figu). It is to be not-ed that the construction shown in Fig. 5 is at the right hand of Fig. 4 since Fig. 4 is a view taken from the rear. The eccentric portions of pm 91 form iio ihr'

combination with the eccentric portions 93 on shaft 93 act to raise and lower the'left end of member 8`as the shaft 93 is rotated, and when the eccentric portions 93 are` in their upinost position, the member 8a, upon which the work pieces are supported is in the working or cutting position. rlhe distance through which the left end of piece 8a is raised or lowered is determined by the throw or eceeiitricity of the portions 93 which is sufficient to provide for the maximum conteniplated depth of cut when the eccentrica are in their upward position while providingthat the work shall clear the cutters to permit indexingv when the eceentrics are in their down position. The support 8 together with the mechanism for misingl and lowering saine, constitutes in elfect, a diop table mechanism whereby the work pieces may be alternately moved to a cutting plane and to a non-cutting plane of movement.

The depth of cut in the work pieces is de.- terinined by the adjustment of the knee 5 vertically oncolumn 1 which bodily moves the work together with its supports toward or fromthe cutters, but in order to piovide an adjustment whereby the depth of cut may be varied at the one end relative to the other, that is to-say at different points in the work piece, the pin 91 is provided with the eccentric portions 91l as previously noted, and the, pin may be rotated to raise or lower the left end of the support Srelative to the pivoted oij righty end, by the means of worin gear teeth 91D, cut in anenlarged portion of pin 91 and eng-aged by a worm or screw 94- suitably sup- -ported for rotation but fixed against axial movement in the part 8 and havineT a shaftor shank fixed with the. worm portion and provided with a squared portion 94a to which a` crank or wrench may be applied for rotating the worin. The pivot about which the support 8 swings is axially parallel with the cultter arbor` and the work pieces are arranged to be equally distant from the pivot axis. although this causes a peculia' arrangement relative to the slide 7. such thaiJ the described adjustment for varying the depth of eut at dill'erent points in the length of the work piece will he equally effeetive upon allwork pieces on the several work centers which very desirable since were it otherwise the axes of the various spindles could not be maintained in a` pla-nc parallel to the axis of the cutter arbor at the different points of adjustment, and each adjustment might then require cutters of different diameter for each work piece in order to obtain equal cut depth on all. Suchjan arrangement is also effective in that the cnt# ter operatingupon each work piece is withdrawn whenv the drop table operates in a direction vertical to the plane of cutter rotation and there can be no undesirable interference The arranoement isy between the work piece and the cutter as the drop table mechanism operates.

A cover plate 95 is hinged at 9G (see Fig. 5A) to protect the mechanism from dust or chips while permitting free access to the squared end 94V for purposes of adjustment. llt may be noted that while for simplicity of drawings the bearings for the pin 91 are shown as bores in the end of part 8, in praeticev the bearings are providedwith removable caps for the convenience of assembly oi the pin.

To rotate the shaft 93 and thereby raise and lower the support 8, transmission mechanism is provided as follows. The shaft has fixed thereon a helical 1gear 97 (see Fig. 6) meshingwvith a. helical gear 98 fixed on ya shaft 99 rotatably supported in the member 7 whereby shaft 99 is driven whenever shaft 55 is driven. At its leftend shaft 99 is suitably supported and provided with a clutch member 100 keyed therewith (see Fig. 19) and supported in a bracket 101 fixed on support 7 and having clutch teeth 100. A. sleeve 102 is freely rotatable on the shaft 99 and carries a gear 103 slidably keyed therewith.

The gear 103 is provided with an extended hub having clutch teeth 103a complementary to the clutch teeth l0()a and urged toward engagement therewith by a spring' 104 housed in a recess or chamber provided between sleeve 102 and the bore of the gear. 'l`he complementary clutch teeth are. normally held from engagement as will be later described but at a certain point in the operation of the device the restrainingr means will be withdrawn or rendered ineliective and the mating; teeth will engage to drive gear 109 from the shaft 99. lVhen so driven the grear 109 will drive a gear 105 with which it meshes and through shaft 100 will drive a worin 107 5, 5A and 18) engaged with a worm The work is supported and may be rotated from individual head spindles 9 (see Figi. il) at the right hand end and from individual tail spindles 10 at the left hand end. in the present embodiment eight of each of these spindles provide for simultaneous operation upon eight work pieces.

rthe eight head spindles are similar in construction and only one will be described in detail. The numerals 9 refer generally to a spindle which consists of a number of parts shown in Fig. 23 in which one of the head spindlesis shown in section. lieferrinaT thereto7 the spindle proper consists of the iiieniber 9"L havin` suitable bearings in the pivoted lill lllfi lll) llfi

lbll 

